Assessment of the immunity gap of two vaccination programs against Gumboro disease in Luong Phuong chicken

Maternal-derived antibody (MDA) is the priority protection against environmental Infectious Bursal Disease Virus (IBDV) in the first weeks. The passive immunity decreases, but the active immunity is not enough to protect chicks, so shortening the high-risk period is crucial to IBD control. The objective of this study was to evaluate the immunity gap between 2 vaccination programs against infectious bursal disease (IBD) in Luong Phuong chickens. A total of 34,600 chicks were administered by subcutaneous injection of IBD vaccine at 0.1 mL/dose at the hatchery. At 12 days old, 18,000 chicks were vaccinated with the M.B strain vaccine and 16,600 chicks were vaccinated with the 228E strain vaccine by drinking water. The IBD and Newcastle disease (ND) antibody evaluations were based on the Enzyme-linked immunosorbent assay (ELISA) technique. Parameters were recorded until slaughter including body weight, average daily gain, feed conversion rate, and mortality. The IBD MDA at 1 day old was medium and uniform (3809 and 45.3%), which could protect against IBD virus from 1 to 2 weeks old. At 28 days old, the IBD antibody titer of the MB vaccine was higher than that of the 228E vaccine, various proportions of samples in the M.B group exceeding 1,000 titers (40% vs. 0%), and it was a statistically significant difference (1,133 vs. 161) (P < 0.01). Besides, the M.B vaccine created a faster and stronger immune response than the 228E vaccine, shortening the immune gap and protecting chicks earlier. The humoral immune response to the ND vaccine was good, with no difference between 2 groups, which proved that the M.B virus did not cause immunosuppression. The production parameters of chickens between the 2 groups were the same. In summary, the M.B vaccine made a short immune gap and did not cause immunodeficiency in chickens.